1. Field of the Invention
This invention relates to a sound suppressor or silencer for a firearm. More particularly, the invention relates to a firearm sound suppressor having the form of a cylindrical casing containing a plurality of baffle members which influence the expanding gases associated with the discharge of a projectile from the muzzle of a firearm in a specific fashion to abate the noise otherwise associated with the firing of the firearm.
2. Brief Description of the Prior Art
Firearm silencers are well known in the art of weaponry, and a variety of constructions have been proposed for minimizing the noise associated with expanding gases at the firing of a weapon. One type of silencer construction can be found by reference to U.S. Pat. No. 1,111,202 to W. E. Westfall. Westfall proposes a casing accommodating a plurality of removable funnel-shaped baffle members arranged so that their smaller openings are directed toward the muzzle of the gun barrel. Outwardly curving faces of the baffle members are purported to act as deflecting surfaces for the exhausting gases. However, such surfaces are, in fact, merely guides, and are not in the direct line of movement of the gases. As a result, many of the gases pass straight through the openings in the series of baffle members.
An alternate form of baffle member in a silencer can be found by reference to U.S. Pat. No. 1,482,805 to H. P. Maxim. Maxim uses a similar series of baffle members faced along a cylindrical casing. However, the disc-like portion of each baffle member is constructed of sheet metal having its center hole deformed by offsetting the opposite edges so that the plane of the aperture is inclined to the axis of the casing. With this arrangement, upon firing the gun to which the silencer is attached, the combustion gases are deflected by the deformed portion of the disc-like member and are directed from one chamber to the succeeding one at an angle to the passage for the projectile. There are several shortcomings of the Maxim silencer, however. Of necessity, the disc-portion of each baffle member must be made thin enough to be deformed by, for example, the bending of a shaft fitted through the aperture and forced off axis of the disc. This would tend to buckle the disc, or at least weaken it, and increasing the thickness of the sheet metal baffle member would, at some point, limit the ability to deform the aperture edges. Moreover, by deforming the aperture edges in the manner described by Maxim, the deformed opposite edges of the aperture are out of the plane of the disc, and the resultant area of the opening is increased to a large extent. This is obviously undesirable when the object of the silencer is to impede the movement of gases along the series of baffle members. Furthermore, in view of the necessity for the baffle members to be formed of thin sheet metal, the use of such silencer would be restricted to small firearms with low muzzle exit pressure. Finally, the surfaces off which the gases deflect are in a position to direct the deflected gases toward the aperture of the next baffle. More importantly, the gases directed by the exit side deformation are directed into the opening in the entrance side deformation of the succeeding baffle member. As a result of these last-two-mentioned physical characteristics, the deflected gases are affected by the deformed disc members in only a small degree, and the gases exiting each baffle member are directed precisely in line with either the aperture or the deformed aperture edge of the succeeding baffle member. Consequently, even with the high number of baffle members illustrated in the Maxim silencer device, the amount of noise reduction is of questionable effectiveness.
The silencer disclosed in U.S. Pat. No. 3,748,956 to Hubner illustrates the use of a series of baffle members which have serrated edges at the passage opening in each baffle member, each serration being bent rearwardly to define a funnel which diverts the gases flowing directly in front of, beside, and behind the projectile. The Hubner silencer thus functions to break up the shock waves produced by the projectile passing through the silencer. The serrated baffles produce a turbulence in the cylindrical column of discharged gases following the projectile and essentially diminishes the energy of the gases by increasing the length of the path taken by the gases before exiting to the atmosphere. The Hubner silencer thus is not adapted to direct the gases passing through the baffle in any specified manner. Rather, Hubner proposes to merely divert the gases prior to exiting each successive baffle member.
In the Waiser U.S. Pat. No. 4,291,610, a series of conical-shaped baffle members are arranged in a manner similar to that described in connection with the Westfall patent. Waiser adds an additional dimension in causing the discharged gases to decrease their energy level by providing a plurality of small holes in a partition member, with the axes of the holes being at an angle with respect to the axis of the silencer. This causes the gases passing therethrough to be directed into the mainstream of gases passing through the main aperture in the center of the silencer device. According to Waiser, the discharged gases are thus separated into a mainstream and into many auxiliary streams with the axes of the auxiliary streams crossing with the axis of the mainstream, resulting in a dispersion of the discharged gases and a decrease of their energy. While the auxiliary streams of the Waiser device are directed into the mainstream of the discharged gases, some of them are angled to direct their discharged gases into the aperture of the downstream baffle member. Accordingly, the gases passing through the auxiliary apertures do not divert the gases away from the opening of the downstream baffle member, in spite of the fact that such auxiliary streams do intersect the axis of the mainstream. Moreover, even in those embodiments which do not direct the auxiliary streams into the opening of the succeeding baffle member, only the partition member is provided with such auxiliary apertures, and the series of baffle members of the Waiser device are devoid of any auxiliary apertures.